The present invention relates to a method for driving a fan wheel of a web-fed printing press, as well as a drive device for the fan wheel, and a delivery module for it.
With known web-fed printing presses, the printed printing substrate, normally a paper web, is conveyed to a folding unit and separated there into individual copies, whereby the individual copies can be collected by means of collect cylinders, etc., to printing products of almost any number of pages. Then the printing products with the desired folding are conveyed to a fan wheel, by means of which they are delivered to a belt delivery. To do so, the fan wheel has externally projecting blades, which, in their progression from the inside to the outside, are curved away from the rotational direction of the fan wheel, wherein a chamber or pocket in which the product is accommodated is formed respectively between a leading and a trailing blade. In the process, the products are slowed down to the fan wheel speed and then, with the aid of a brush-out belt for example, deposited on the belt delivery in an orderly manner in so-called shingle delivery.
However, it has emerged that thick and/or rigid products as well as electrostatically charged products tend not to slide all the way into the base of the fan wheel chamber after exiting the conveyor belt to the fan wheel. This is because electrostatically charged products get “stuck” to the surface of the blades before reaching the target position and thick and/or rigid products do not conform to the curvature of the blades of the fan wheel, but tend to get wedged between a blade and the next subsequent blade. In both cases, the product does not reach the chamber base between the blade and subsequent blade and projects beyond the outer circle of the fan wheel, with the consequence that the subsequent product nudges against the leading product and does not slide into the chamber, which leads to jam-ups, or, if the products do reach the belt delivery, to diminished delivery quality in any case.
A delivery module with this type of fan wheel, an individual drive of the fan wheel, as well as a corresponding belt delivery is disclosed in German Patent Document No. DE 10 2004 029 170 A1, for example. This already discloses a delivery module, which can be adjusted in terms of its horizontal, vertical as well as its angular position with respect to the folding unit. The position of the fan wheel can be adjusted therewith in such a way that the products are transferred with positional accuracy to the blades of the fan wheel irrespective of product width, strength and thickness, thereby achieving an improved delivery quality, but not eliminating the principle problem cited in the foregoing.
Starting herefrom, the subject of the present invention is creating a method for driving a fan wheel of a web-fed printing press as well as a drive device suitable for it and a suitable delivery module, with which the delivery quality can be further improved and jams in the press can be avoided.
According to the invention, it is provided that the fan wheel be driven, at least in a predetermined time period in the production cycle, in a vibrating manner, i.e., with an oscillating fan wheel speed. The drive device according to the invention is therefore correspondingly embodied to drive the fan wheel with the oscillating fan wheel speed, preferably in the predetermined time period in the production cycle, in particular during power-up of the printing press. In addition, the delivery module is embodied according to the invention in such a way that the fan wheel is driven with the oscillating fan wheel speed, preferably in the predetermined time period in the production cycle, in particular during power-up of the printing press.
The fan wheel is induced to vibrate in this manner. As a consequence of the vibrations, no static friction occurs between the blade and the printing product so that the product does not get “stuck” halfway. In fact, a proper conveyance behavior in the direction of the fan wheel base takes effect. The printing product is “shaken” into the fan wheel chamber up to the target position. As a whole, the production reliability of the web-fed printing press is greatly improved with the correspondingly driven fan wheel.
The predetermined time period in the production cycle can extend over the entire production duration. However, it advantageously extends only over phases in which the fan wheel is operated below a specific critical rotational speed, especially when powering up but also when shutting down the printing press. This is because it has emerged that starting at a specific rotational speed, which depends, in-turn, on parameters such as the work cycle of the printing press, the structure of the fan wheel and the quality of the printing product, an adequate inherent momentum of the printing product is present so that, even without the oscillating drive of the fan wheel, it reaches the chamber base or penetrates far enough into the chamber to ensure good delivery quality.
During start-up of the printing press, an oscillating speed component can thus be applied to a rotational speed of the fan wheel, which increases for example according to a target value ramp predetermined by the controller or regulating unit of the fan wheel drive, until the critical rotational speed is achieved, from which point on the inherent momentum of the printing products suffices. In this case, the target value can be used as the critical rotational speed or an actual value measurement can be performed, whereby a fixed value from which point on the inherent momentum of the printing products suffices in any case can be specified as the critical rotational speed, or, if a corresponding adjustment possibility is provided, adjustments can be made product-specifically in terms of the parameters of the product in the respectively manufactured lot.
In this case, it is conceivable, on the one hand, to allow the fan wheel rotational speed to oscillate or to superimpose an oscillating rotational speed component on the predetermined target rotational speed so that the fan wheel oscillates or vibrates in the circumferential direction. This is frequently relatively easy to implement in terms of the structural effort in the case of conventional fan wheels or delivery modules since an individual drive is provided here for the fan wheel in most cases. The individual drive can then be triggered with a target rotational speed, which has an oscillating component. Alternatively or as a supplement thereto, it would also be possible, on the other hand, to set the fan wheel into oscillation in the axial or radial direction.
Especially in the former case, the drive device can advantageously have a rotary drive, which supplies the oscillating rotational speed to the fan wheel, for example, an electric motor 25a and/or a current converter 25b. An oscillation, e.g., in the form of an oscillating input voltage, can then be superimposed on the normal operating curve of the drive regulation (rotational speed as a function of time) of the electric motor and/or current converter. Thus, a fine adjustment of the rotational speed oscillation with respect to the changing oscillation amplitude or oscillation frequency can be made as a function of the momentary rotational speed, if this should be necessary.
In the second case, a horizontally or vertically, or axially or radially displaceable support of the fan wheel can be provided, as well as a corresponding linear drive, with which the fan wheel can also driven in an oscillating manner in the radial or axial direction in addition to the rotational movement. This is advantageous in particular in the case of such a delivery module, which, as in Document DE 10 2004 029 170 A1 that was already mentioned at the outset, already has a horizontally displaceable substructure.
Alternatively or as a supplement, the fan wheel could also be attached in a swiveling manner to an axially parallel suspension and an oscillating swivel movement could be superimposed on the rotational movement of the fan wheel.
Finally, it would also be conceivable to rotationally drive the fan wheel free of oscillations and merely set the blades into oscillation.
Advantageous developments are explained in greater detail along with additional preferred developments of the invention in the following on the basis of the enclosed drawings. The invention is not limited hereto, however. In fact, the features of the claims and the embodiment described in the following can be combined in any combination without departing from the scope of the invention.